The adoption of a low-GWP refrigerant gas in MAC systems is mandatory from January 1st, 2017 according to the European Directive 2006/40/EC requirements for all new passenger cars, in order to gain their registration in the EU28 market.
Following the work carried out in 2008 to support the FCA choice for the new types development, a further step was accomplished to evaluate the risk involved by the adoption of the low-GWP refrigerant gas R-1234yf in the MAC systems. This paper is focused on the activities held to enhance the 3D CFD method and its validation.
In certain concentrations, R-1234yf could present a safety hazard to the vehicle occupants and, according to the ISO Standard Risk Scenario evaluation, 3D CFD tools are adopted to evaluate the ignition event associated with small or large leak in the passenger compartment.
The method validation has been supported by both a simplified control volume “dummy cabin compartment” and an actual FCA vehicle. Methods have been used to measure the actual R-1234yf concentrations due to a complete system charge leakage in an HVAC configuration representative of the worst case operating conditions.